Simulation of flame-dynamics of a premixed swirl injector in a model gas turbine engine

A comprehensive numerical analysis has been conducted to study the combustion dynamics of a lean-premixed swirl injector in a model gas turbine engine. The analysis treats the conservation equations in three dimensions, and takes into account finite-rate chemical reactions and variable thermophysical properties. Turbulence closure is achieved using a large-eddy-simulation (LES) technique. The governing equations and the associated boundary conditions are solved by means of a semi-implicit Runge-Kutta scheme along with the implementation of the message passing interface (MPI) parallel computing architecture. Results from the study of a non-reacting swirling flow indicate reasonable agreement with experimental data in terms of both the time-averaged velocity components and turbulence quantities. The unsteady turbulent flame dynamics are carefully simulated so that the oscillatory combustion behavior can be characterized in detail. Good agreement with experimental data is observed in terms of acoustic properties and flame evolution. Several mechanisms responsible for driving combustion instabilities have been identified and quantified. In addition, the basis modes of the unsteady turbulent flame are characterized using a proper orthogonal decomposition (POD) analysis.